Browsing by Subject "lepotila"

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  • Wood, Steffaney M.; Kremp, Anke; Savela, Henna; Akter, Sultana; Vartti, Vesa-Pekka; Saarni, Saija; Suikkanen, Sanna (Frontiers in Microbiology, 2021)
    Frontiers in Microbiology 12
    Cyanobacteria of the order Nostocales, including Baltic Sea bloom-forming taxa Nodularia spumigena, Aphanizomenon flosaquae, and Dolichospermum spp., produce resting stages, known as akinetes, under unfavorable conditions. These akinetes can persist in the sediment and germinate if favorable conditions return, simultaneously representing past blooms and possibly contributing to future bloom formation. The present study characterized cyanobacterial akinete survival, germination, and potential cyanotoxin production in brackish water sediment archives from coastal and open Gulf of Finland in order to understand recent bloom expansion, akinete persistence, and cyanobacteria life cycles in the northern Baltic Sea. Results showed that cyanobacterial akinetes can persist in and germinate from Northern Baltic Sea sediment up to >40 and >400 years old, at coastal and open-sea locations, respectively. Akinete abundance and viability decreased with age and depth of vertical sediment layers. The detection of potential microcystin and nodularin production from akinetes was minimal and restricted to the surface sediment layers. Phylogenetic analysis of culturable cyanobacteria from the coastal sediment core indicated that most strains likely belonged to the benthic genus Anabaena. Potentially planktonic species of Dolichospermum could only be revived from the near-surface layers of the sediment, corresponding to an estimated age of 1–3 years. Results of germination experiments supported the notion that akinetes do not play an equally significant role in the life cycles of all bloom-forming cyanobacteria in the Baltic Sea. Overall, there was minimal congruence between akinete abundance, cyanotoxin concentration, and the presence of cyanotoxin biosynthetic genes in either sediment core. Further research is recommended to accurately detect and quantify akinetes and cyanotoxin genes from brackish water sediment samples in order to further describe species-specific benthic archives of cyanobacteria.
  • Höyhtyä, Riitta; Hänninen, Heikki (Suomen metsätieteellinen seura, 1991)
  • Hänninen, Heikki; Pelkonen, Paavo (Suomen metsätieteellinen seura, 1988)
  • Hänninen, Heikki (Suomen metsätieteellinen seura, 1987)
  • Valkonen, Marja-Leena; Hänninen, Heikki; Pelkonen, Paavo; Repo, Tapani (Suomen metsätieteellinen seura, 1990)
  • Nygren, Markku (Suomen metsätieteellinen seura, 1987)
    Tests on seeds from a natural stand and from a clone archive, with various photoperiods and temperature regimes, showed that germination was delayed at low temperature (10 degrees C) and in darkness. This effect diminished the later in autumn seeds were collected.
  • Hintikka, Veikko (Suomen metsätieteellinen seura, 1987)
  • Hänninen, Heikki (Suomen metsätieteellinen seura, 1986)
  • Hänninen, Heikki (The Society of Forestry in Finland - The Finnish Forest Research Institute, 1990)
    A model of the effects of air temperature on bud dormancy release was developed on the basis of experimental results with two-year-old seedlings of Pinus sylvestris and Picea abies and a study of previous models. Bud dormancy is generally released when buds are exposed first to chilling temperatures (e.g. -5 degrees C to 10 degrees C) and then to forcing temperatures (e.g. >0 degrees C). Seedlings from a central and a northern Finnish provenance of Pinus sylvestris, and from a central Finnish provenance of Picea abies, were raised in paper pots in a mixture of peat and sand, and grown outside. At the end of the second growing season, the seedlings were transferred to dark growth chambers and subjected to chilling conditions. In one experiment the chilling took place outside. The seedlings were then subjected to forcing temperatures (12-22 degrees C) in growth chambers. Bud burst was said to have occurred if the total growth of the terminal bud exceeded 5 mm. Behaviour of the Finnish material differed from that predicted by models based on studies of more southerly provenances. The new model is described, and further model development outlined.
  • Kemppinen, Johanna (Helsingfors universitet, 2017)
    Blackcurrant (Ribes nigrum L.) is a woody plant in cold regions and it adapts well for the Finland’s boreal zone. There were less than 600 companies farming blackcurrant and green currant in 2014 and the acreage was 1449 ha and the level of yield was over 1000 kg/ha. In year 2016, the number of companies were 544 and the acreage was 1435 ha and the level of yield less than 1000 kg/ha. There has been a pressure to reduce the high price of domestic blackcurrant, due to that the inexpensive imported berries have been taken more position in industry. The global warming can be a serious threat for the cultivation of blackcurrant in the future. There is a need for new cultivars of blackcurrant in Finland and the objective of this research was to examine the depth and reversal of on dormancy on various points of time and the resilience of winter. For the results the bud burst was monitored in quantity and temporal on forcing. The processing of release of dormancy in various temperatures and light conditions before the forcing was also included to the research. The cold hardiness was tested in temperatures, which was descending step by step in controlled sub-zero experiment. The results demonstrated that the bud burst was the lowest during the deepest dormancy in OctoberNovember and the largest in February, when the dormancy was already released. ‘Almiai’ and ‘Gagatai’ were the best cultivars, which were able to maintain the dormancy; in first forcing in October, bud burst 0 %. The bud burst was particularly substantial in February and ‘Ben Tron’ the bud burst was even 80 %. In October-November the time elapsed for bud burst was highest and least was in February with average of 10 days. The most optimal temperature in dormancy release was 0 ⁰C. On the cultivar ‘Mikael’ the bud burst was quicken in +18 ⁰C . The longer the processing time was, the shorter was the time for bud burst. The temperatures +12 ⁰C and +18⁰C were too high for dormancy release. In cold hardiness, the cultivars didn’t differ much from each other. The results demonstrate that the cultivars differ from each other in the depth of dormancy and release. ‘Almiai’ and ‘Gagatai’ maintained best their dormancy. These cultivars could be suitable options for farming in Finland. They were also winter hardiness. In the future, there should be breeding of blackcurrant cultivars, which adjust different kind of environments. Additionally, we should discover and breed cultivars, which have good resistant for winter and maintain dormancy, even though the temperatures are varying in winter.
  • Nygren, Markku (Suomen metsätieteellinen seura, 1986)